Gravitational lens recovery with glass: measuring the mass profile and shape of a lens

We use a new non-parametric gravitational modelling tool { Glass { to determine what quality of data (strong lensing, stellar kinematics, and/or stellar masses) are required to measure the circularly averaged mass prole of a lens and its shape. Glass uses an under-constrained adaptive grid of mass pixels to model the lens, searching through thousands of models to marginalise over model uncertainties. Our key ndings